Saying "everything is extremely slow" does not allow a prognosis without
more specific info.

Debian Linux in general allows you to fine-tune a Linux installation and
use the superior Debian packaging system but is meant for those who are
knowledgeable or those who are willing to learn and read the manuals.
(Which I do badly ;-) )

There is no such thing as upgrade Red Hat to Debian: they are two
different distros with different objectives, each excelling in their own
areas.

If you are new to Linux and want to learn Debian there are several options:

1. Use a Debian distro that is already pre-packaged, e.g. Knoppix, there
are others. Use Google to search.
2. Use Debian as is from minimum CD, full CD or boot floppies. Described
in http://www.debian.org

In the latter case: be patient and read the manuals, it is not meant to
be an install on the fly: you are building a finely-tuned machine.

We will help you when you specify specific problem areas in detail.
Hugo.